The effective regulation of behavioral and physiological reactivity during the first years of life has been associated with successful regulation of behavior in later years (Sroufe, Egeland, & Carlson, 1999). The ability to regulate arousal has been linked to successful adaptation to the tasks of early school adjustment, leading in turn to better academic achievement (Pintrich, 2000) and school performance (e.g., Bull & Scerif, 2001). It is well established that caregivers play an important role in helping infants and young children develop self- regulatory skills (Calkins, 1994). Furthermore, as children enter school their relationships with teachers become integral in continuing to shape self-regulatory processes (Hamre & Pianta 2005). The current study was designed to identify predictors of academic achievement across these multiple levels. The preschool period is a critical time for studying children's regulatory abilities, given the rapid development of executive function during this stage of life (e.g., Diamond, 2002) and the convergence of cognitive and emotional processes that are crucial for school readiness (Blair, 2002). The current study was designed to explore children's self-regulation in the preschool (Pre-K) classroom as a function of the interplay between 1) children's behavioral and physiological self-regulation in toddlerhood, 2) early parenting behaviors, and 3) concurrent teacher behaviors. We build on existing studies of self-regulation within the early parent- child relationship and extend this line of research to include the unique contribution of the teacher-child relationship that occurs in the early classroom context. Furthermore, this is the first study of which we are aware in which physiological (i.e.,vagal tone) measures of regulation will be collected in the classroom context. The proposed short-term longitudinal study will include assessments at 3.5, 4, and 4.5 years of age (N = 100). Observational, physiological, and maternal- and teacher- report measures of child functioning will be obtained. At two home visits (age 3.5 and 4.5), child self-regulation (behavior and respiratory sinus arrhythmia [RSA]; vagal tone), temperament, early cognitive/executive functioning, and the parent-child relationship will be measured. In the classroom (Pre-K; age 4), we will collect child-level measures of self-regulation (behavior and RSA) and academic performance. Moreover, we will collect classroom-level measures (e.g., teacher sensitivity and support) using the Classroom Assessment Scoring System (CLASS) (Pianta & La Paro, 2003). Higher self-regulation has been associated with better long-term academic achievement and school performance (BulI & Scerif, 2001). Although the capacity to regulate one's own emotions in toddlerhood is a crucial pre-requisite for effective self-regulation in the classroom, these two processes are typically discussed in separate literatures. This study will be a first attempt at examining the interplay between children's physiological functioning and their interactions with parents and teachers in order to predict successful self- regulation in the early classroom context as well as early academic skills.